Tracking highly enriched uranium and plutonium, the key nuclear weapon materials
 

Managing nuclear spent fuel: Policy lessons from a 10-country study

| 0 TrackBacks

BULLETIN OF THE ATOMIC SCIENTISTS | 27 JUNE 2011

BY HAROLD FEIVESON, ZIA MIAN, M. V. RAMANA, AND FRANK VON HIPPEL

The International Panel on Fissile Materials is in the process of finalizing an analysis of the policy and technical challenges faced internationally over the past five decades by efforts at long-term storage and disposal of spent fuel from nuclear power reactors. These challenges have so far prevented the licensing of a geological spent fuel repository anywhere in the world.

Here we summarize the findings of this report on the history and current status of radioactive waste management in ten countries. The case studies include four countries that reprocess nuclear spent fuel (France, Japan, Russia, and the United Kingdom), five countries that are planning on direct disposal of spent fuel (Canada, Finland, Germany, Sweden, and the United States) and one country (South Korea) whose disposal plans are a subject of discussions with the United States as part of the renewal of a bilateral nuclear cooperation agreement.

Introduction. Nuclear power reactors are fueled mostly with low-enriched and natural uranium, which undergoes a fission chain reaction releasing heat and creating radioactive fission products and plutonium and other transuranic elements. The heat is used to produce steam to drive turbines that produce electricity. Eventually, the concentration of chain-reacting isotopes drops to the point where the fuel is considered "spent" and has to be replaced with fresh fuel.

The intensely hot and highly radioactive spent nuclear fuel from power reactors is unloaded into a water-filled pool immediately adjacent to the reactor to allow its heat and radiation level to decrease. It remains in this pool for periods ranging from a few years to decades. After cooling, the fuel may be transferred to massive air-cooled dry casks for storage on site or in a centralized facility.

In a few countries, spent fuel is sent to a reprocessing plant, where the fuel is dissolved and the plutonium and uranium recovered for potential use in reactor fuel. These processes also produce high-level wastes that contain the fission products and other radioisotopes from the spent fuel -- as well as other streams of radioactive waste, including plutonium waste from the manufacture of plutonium-containing fuel.

It is widely accepted that spent nuclear fuel and high-level reprocessing and plutonium wastes require well-designed storage for periods ranging from tens of thousands to a million years, to minimize releases of the contained radioactivity into the environment. Safeguards are also required to ensure that neither plutonium nor highly enriched uranium is diverted to weapon use. There is general agreement that placing spent nuclear fuel in repositories hundreds of meters below the surface would be safer than indefinite storage of spent fuel on the surface.

The spent fuel inventories for the ten countries covered in this study, as of the end of 2007, are shown in Table 1. They account for about 70 percent of the global stock of spent fuel. The United States has the largest spent fuel stockpile; by the end of 2010, the total US stockpile of spent power-reactor fuel was 64,500 tons, including 15,350 tons in dry casks, according to the US Department of Energy's Office of Disposal Operations.

Country

Spent Fuel Inventory
(tons of heavy metal)
End of 2007

Spent Fuel Policy

Canada

38,400

Direct disposal

Finland

1,600

Direct disposal

France

13,500

Reprocessing

Germany

5,850

Direct disposal (now)

Japan

19,000

Reprocessing

Russia

13,000

Some reprocessing

South Korea

10,900

Storage, disposal undecided

Sweden

5,400

Direct disposal

United Kingdom

5,850

Reprocessing but future unclear

United States

61,000

Direct disposal

Table 1. Spent fuel inventories in cooling ponds and dry-cask storage, as of the end of 2007, for the countries in the IPFM study. These numbers come mostly from national reports under the Joint Convention on the Safety of Spent Fuel Management and the Safety of Radioactive Waste Management. The country chapters in the forthcoming IPFM report will have more detail, and some include estimates for years after 2007. The term "heavy metal" indicates that the fuel mass is being measured by its original uranium or uranium-plus-plutonium content, i.e. not including the weight of structural materials or the oxygen in the uranium and plutonium oxides.

Reprocessing and radioactive waste policies. Countries initially justified civilian reprocessing by the need for separated plutonium to provide startup fuel for plutonium breeder reactors, but breeder reactors have not materialized. A 2010 IPFM report examined the efforts to commercialize fast breeder reactors in six countries and showed how cost and reliability problems defeated these efforts. Some countries are therefore recycling their separated plutonium back into the reactors that produced it -- as uranium-plutonium "mixed-oxide," or MOX, fuel. Now some are advocating reprocessing as necessary for dealing with spent fuel.

Reprocessing does not eliminate the requirement for a repository, however, or even reduce its size much. This is because, in effect, reprocessing merely exchanges the problem of managing light-water-reactor spent fuel for the problem of managing not only spent MOX fuel but also the high-level waste from reprocessing, plutonium waste from MOX-fuel fabrication, and eventually the waste from decommissioned reprocessing and MOX-fuel fabrication facilities.

Finally, reprocessing does not reduce the political challenges to repository siting. This is illustrated by the impasses over repository siting in Japan and the United Kingdom, both of which reprocess spent fuel. By contrast, Sweden and Finland, the countries that are most advanced in repository siting, do not reprocess their spent fuel.

Geological repository siting. Finding sites for repositories has proven politically very difficult. The first approach pursued by nuclear establishments has been "top-down," with central governments deciding which sites should be considered for repositories. This has almost always resulted in strong local opposition, leading to the abandonment of the sites. The authors of our United Kingdom case study describe this sequence by the acronym DADA: Decide, Announce, Defend, and Abandon.

The Obama administration's decision to abandon the Yucca Mountain repository project provides only the most recent example. In the United Kingdom, in 1981, in the face of intense local opposition, the government abandoned efforts to investigate the geology at possible sites that it had identified for a high-level repository and decided not to resume the effort for 50 years. And in Germany, in 1977, the federal government, the state government of Lower-Saxony, and the nuclear industry chose Gorleben as a place to dispose of spent fuel and high-level reprocessing waste. The site became the focus of huge demonstrations and, in 2000, the government halted work there. In 2009, a successor government allowed further exploratory work at Gorleben, triggering renewed protest.

After such initial failures, several countries have sought to develop a more consultative process in which local communities determine whether or not they wish to be included in site assessments. There is often also a greater role in this type of process for stakeholders that are independent of the nuclear utilities and the government.

Finland and Sweden provide the most advanced examples of this participatory approach. Starting in the early 1990s, SKB, a company established by Sweden's nuclear utilities, began a voluntary process for siting a spent-fuel repository. Initial attempts to site the repository in the north of the country were ended by local referenda. Sweden then moved on to other sites that already had nuclear facilities. Even among these, some rejected the idea of hosting a geological repository. The two remaining sites were offered about $300 million between them as compensation for their willingness to host the repository. Finally, the Forsmark site, which already hosts a nuclear power plant, was selected with the support of 80 percent of the local population. A license application to construct a repository at this site was submitted in March 2011.

In Finland, the 1987 Nuclear Energy Act and its 1994 amendment gave municipalities the right to veto any nuclear facilities, including waste repositories, in their areas. In the end, only one community, next to the Olkiluoto nuclear plant, volunteered to host a repository.

In many countries, the initial idea behind a geological repository was that the geology, in and of itself, would prevent public exposure to the radiological hazard from spent fuel. The United States and Germany focused initially on salt beds because they were self-sealing, and France and Switzerland have focused on clay beds for the same reason. Sweden is underlain by granite, and its radioactive-waste disposal organization, SKB, discovered that it could not find any large block that was crack-free. Cracks offer pathways for the movement of water and leachates from the spent fuel or waste. SKB therefore designed a 5-centimeter-thick copper cask that it believed would not corrode through for a million years. The plan is to surround the cask with a thick layer of bentonite clay, which swells and becomes almost impermeable when wet.

Both approaches have encountered problems. Human-made water channels often have penetrated salt beds, and experiments have found that copper corrosion rates may be much higher than originally projected by SKB. It appears that both favorable geology and engineered barriers will be required to prevent radioactivity from eventually reaching the surface.

Reversible repositories. Given the uncertainties in repository performance and the possibility that reprocessing may appear more attractive in the future, there has been interest in keeping underground disposal reversible. In Canada, the Nuclear Waste Management Organization recommended a retrievable period of approximately 240 years. France's 2006 radioactive waste law specifies that no license for a repository for long-lived intermediate and high-level radioactive wastes shall be granted "if the reversibility of such a facility is not guaranteed." Making it easy for the spent fuel and waste to be retrievable from the repository for long periods of time may, however, make the challenge of safeguards more difficult.

The International Atomic Energy Agency (IAEA) currently monitors spent fuel and reprocessing plants in non-nuclear-weapon states. The IAEA is also considering how to monitor spent fuel at repositories. This is necessary because the huge quantities of plutonium contained in the spent fuel could become a long-term proliferation risk -- although much less in the near term than the proliferation risk from reprocessing.

The IAEA has determined that, "with appropriate advanced planning, the operational and safety impacts of applying routine traditional IAEA safeguards in a geological repository is no greater or more technically challenging than those affecting other types of nuclear facilities." The safeguarding of a geological spent fuel repository would have to be of indefinite duration, but the means to ensure continuity of the responsible institutions and knowledge on time scales exceeding thousands of years is unknown.

Dry-cask storage as an interim strategy. With most spent fuel pools full or nearly full, and reprocessing and repositories delayed, the use of dry-cask storage for older spent fuel is becoming common, including in the United States, Canada, Germany, South Korea, and Russia. In dry-cask storage, spent fuel assemblies are typically placed in steel canisters that are surrounded by a heavy shell of reinforced concrete with vents that allow cooling air to flow through to the wall of the canister. There are a variety of cask types in use. Some countries store casks in buildings for additional protection against weather damage, accidents, and attack.

An IAEA report notes that "long term [dry-cask] storage [is] becoming a progressive reality ... storage durations up to 100 years and even beyond [are] possible." The cost of dry-cask spent fuel storage is low -- only about $100 to $200 per kilogram of contained heavy metal in the United States, where the casks are stored outdoors. In Germany and Japan, storage is inside thick-walled buildings, which can double the cost. This is still low, however, compared with the more than $1,000-per-kilogram cost of reprocessing.

In the United States, as of the end of 2010, about 70 percent of all sites with operating nuclear reactors had associated dry storage facilities. US citizen groups have indicated that they prefer hardened, on-site dry-cask storage to reprocessing. In most cases, centralizing storage would create unnecessary cost and exposure of spent fuel to transportation hazards.

Importing foreign spent fuel. Foreign spent fuel has been imported into France, the United Kingdom, and Russia for reprocessing. In the cases of France and the United Kingdom, however, all but the earliest reprocessing contracts stipulate that the resulting high level wastes -- and in most cases, the recovered plutonium and uranium -- must be sent back to the country of origin. According to France's 2006 law, "no radioactive waste, whether originating from a foreign country or from the processing of foreign spent fuel and foreign radioactive waste, shall be disposed in France." The United Kingdom has a similar requirement.

In Russia, although the law gives the government considerable discretion with regard to the import of spent foreign fuel, opinion polls show 90 percent of the public opposed to importing spent fuel that is not "Russian origin," i.e., originally provided by Russia. The reprocessing waste from Russian-origin fuel can be left in Russia. Most of the Russian-origin fuel that Russia has repatriated has not been reprocessed in Russia's existing reprocessing plant, however, but is in long-term storage pending the construction of a larger reprocessing plant.

Multinational repositories. The idea of countries sharing a geological repository has been around since the 1970s. Three efforts in the 1990s to consider an international repository -- involving the Marshall Islands, Palmyra Island, also in the Pacific, and a site in western Australia -- were blocked by determined public opposition. The idea resurfaced in the 2000s but, to date, no country has volunteered to host a multinational spent fuel repository. In Finland and other countries, understandings relating to the siting of national repositories have included a commitment that only national waste will be disposed at that site. The widespread belief that each country has an ethical responsibility to manage its own nuclear waste may be an enduring obstacle to hopes for a multinational spent fuel repository.

Nuclear waste and the future of nuclear power. Practically all stakeholders, whatever their views of nuclear power, realize that spent fuel and any high level waste generated by existing nuclear programs must be disposed of eventually. The possibility of constructing new nuclear reactors, however, destroys this near consensus. Those opposed to an expansion of nuclear power feel that allowing for the disposal of existing waste removes one of the major obstacles to constructing new nuclear reactors. They have therefore supported geological disposal only when it is part of a commitment not to construct any new reactors.

In the United Kingdom, the Committee on Radioactive Waste Management, in drawing up a proposed national disposal policy, sought to draw a clear distinction between legacy waste and "new-build" waste. Canada's Nuclear Waste Management Organization has made a similar distinction.

In Germany, a coalition government of the Social Democrats and the Green Party decided in 2000 to phase out nuclear energy, partly in response to the contentious problem of nuclear waste management. The Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety has observed that, along with the risks from operating nuclear reactors, "A problem yet to be solved... is the management of the radioactive wastes from nuclear power plants. Such wastes remain radioactive for millions of years -- a dangerous legacy for future generations. For this reason the Federal Government decided to completely phase out the production of electricity from nuclear power." A subsequent coalition government of Christian Democrats and Liberals in 2009 delayed the scheduled phase-out, but reversed its position after the March 2011 Fukushima reactor accidents in Japan. Germany has now shut down eight nuclear reactors and plans to shut down its remaining nine reactors between 2015 and 2022. It is too early to judge whether this decision will clear a path for siting a spent fuel and high-level waste repository in Germany.

No TrackBacks

TrackBack URL: http://fissilematerials.org/cgi-bin/mt/mt-tb.cgi/1802